Pension Benefits and Other Postretirement Benefit Plans (Additional Information) (Details) $ in Thousands			2 Months Ended		3 Months Ended	9 Months Ended
	Oct. 30, 2019 USD ($)	Oct. 18, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) plan	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of qualified noncontributory defined benefit plans | plan						2
Pension assets						$ 20,236		$ 19,273
Voluntary contributions						$ 16	$ 25,347
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Voluntary contributions					$ 25,000		$ 25,000
Subsequent Event | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Payment for settlement		$ 124,000
Lump sum distributions	$ 39,000
Forecast | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Payment for settlement				$ 1,000
Minimum | Forecast | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Settlement charge			$ 52,000
Pension assets			7,000	7,000
Maximum | Forecast | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Settlement charge			56,000
Pension assets			$ 11,000	$ 11,000